In assisted breathing, and particularly in medical applications such as artificial ventilation, gases having high levels of relative humidity are supplied and returned through flexible breathing tubes of a relatively restricted size typically between a range of approximately 10 mm to 35 mm diameter (covering both neonatal and adult applications). Continuous Positive Airway Pressure (CPAP) systems or positive pressure ventilation systems that provide patients suffering from obstructive sleep apnoea (OSA) with positive pressure breathing gases, also use this sort of breathing tubes for delivering (or removing) inspiratory (and/or expiratory) gases.
Such breathing tubes are ideally very light, resistant to kinking or pinching, to ensure the greatest performance and level of comfort for the patient. The relatively light weight of a breathing tube is important to reduce any forces applied to the patient interface by the weight of the tube. Similarly, breathing tubes must be flexible and able to bend easily to achieve a high level of patient comfort, which in turn, can improve patient compliance with therapy. However, extremely light and flexible breathing tubes may be weak and prone to excessive kinking and/or stretching which can interfere with the ventilation therapy. For example blocking/pinching of the breathing tube or excessive stretching may reduce the ventilators ability to accurately detect patient breaths and trigger appropriately.
Breathing gases inhaled/exhaled by a patient are preferably in a condition having humidity near saturation level and at close to body temperature (usually at a temperature between approximately 33° C. and 37° C.). These conditions present a significant risk of condensation forming in the breathing tubes which is highly undesirable. In order to minimise condensation formation and to ensure breathing gases are delivered at the appropriate elevated temperature, breathing tubes may include an associated heater to heat the breathing gases. The addition of a heater (usually in the form of a heater wire inside the tube) requires electrical connections and terminations to complete the electrical circuit and receive power. These additional requirements add significant complexity to the breathing tube, and are often completed manually.
The term “comprising” as used in this specification and claims means “consisting at least in part of”. When interpreting each statement in this specification and claims that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.